1. Field of the Invention
The present disclosure relates to a trench power semiconductor and a method of making the same; more particularly, to a trench power semiconductor component having a shielding electrode and a method of making the same.
2. Description of Related Art
Power loss in a conventional power metal oxide semiconductor field transistor (Power MOSFET) can be classified into two types, switching loss and conduction loss. Drain-to-gate capacitance is an important parameter in switching loss. A high drain-to-gate capacitance leads to the increase in switching loss, thereby limiting the switching rate of power MOSFETs. Therefore, a power MOSFET of high gate-to-drain capacitance is not suitable for high frequency circuits.
Power MOSFETs in the prior art include a shielding electrode located in the lower half part of the trench gate so as to reduce the gate-to-drain capacitance and increase the breakdown voltage without adversely affecting the on-resistance. In this way, the thickness of the epitaxial layer as well as the resistance value can be optimized.
However, the two side walls of the trench may be oxidized when performing a thermal oxidation process to form an inter-electrode dielectric layer that separates the shielding electrode and the gate electrode, which results in a deviation in the width of the trench from that originally designed.